1. Field of the Invention
The present disclosure relates to liquid crystal display technology, and more particularly to a liquid crystal panel and a liquid crystal display (LCD).
2. Discussion of the Related Art
LCDs are characterized by attributes such as thinner, power-saving, low radiation, and so on, and thus are greatly adopted. Currently, most of the LCDs are backlight-type, including a liquid crystal panel and a backlight module. Liquid crystal molecules are arranged between two parallel glass substrates. The alignment of the liquid crystal molecules are controlled by applying a voltage to the glass substrates such that the light beams from the backlight module are reflected to generate images.
The liquid crystal molecules alignment is the key technology regarding liquid crystal display. The alignment plays an important role in display performance. High quality images can only be obtained by stably and uniformly arranged liquid crystal molecules. Generally, alignment layers, which are thin layers, are adopted to align the liquid crystal molecules. Currently, Polymer Stabilized Vertical Alignment (PSVA) LCDs, made by Polymer Stabilized Alignment (PSA) process, are characterized by attributes such as wide viewing angle, high aperture rate, and high contrastness, and thus are greatly adopted.
Regarding the PSVA LCDs, the liquid crystals between the two transparent substrates are doped with reactive monomer. Surfaces of each of the transparent substrate coated with polyimide (PI) are the alignment substrates. Afterward, the two transparent substrates are applied with the voltage and are irradiated by ultraviolet rays (UV). Phase separation phenomenon occurs by the reactive monomer and the liquid crystals so as to form polymer on the alignment substrates. The liquid crystals are aligned along the direction of the polymer due to the interaction between the polymer and the liquid crystals. Thus, the liquid crystal molecules between the transparent substrates have the pre-tile angle.
Referring to FIG. 1, the conventional liquid crystal panel includes an up substrate 210, a down substrate 220 opposite to the up substrate 210, and a liquid crystal layer 250. The up substrate 210 is a thin film transistor (TFT) array substrate. The down substrate 220 is arranged a color filer (CF) layer 240 and a black matrix 230 arranged above the down substrate 220. During the PSVA alignment process, UV rays irradiate from one side of the up substrate 210 such that the UV rays are prevented from being absorbed by the CF layer 240 and the black matrix 230. As such, the reactive monomer 252 is separated from the liquid crystal molecules 251, and the polymer are formed on the alignment substrate of the up substrate 210 and the down substrate 220. However, the above liquid crystal panel has a lower resolution, and the aperture rate of pixels is also low. In addition, the misalignment may occur when bonding the CF layer 240 with the TFT array substrate.
Recently, a new technology “color filter on array (COA)” is proposed, which relates to directly bonding the CF layer on the TFT array substrate, which would not results in misalignment. In addition, the liquid crystal panel has better resolution, and the aperture rate of the pixel is also higher. Referring to FIG. 2, the conventional COA liquid crystal panel includes a first substrate 110, a second substrate 120 opposite to the first substrate 110, and a liquid crystal layer 150 arranged between the first substrate 110 and the second substrate 120. The first substrate 110 includes a display area 111 having the black matrix 130 and a peripheral area 112 surrounding the display area 111. The second substrate 120 is the TFT array substrate. The second substrate 120 includes a color filter layer 140 having a red color filter unit 141, a green color filter unit 142, and a blue color filter unit 143. During the PSVA alignment process, the UV rays irradiate from one side of the first substrate 110. However, as the black matrix 130 on the peripheral area 112 of the first substrate 110 absorbs the UV rays, residues of the reactive monomer may be left on the liquid crystal layer 150. After being driven for a long time period, the reactive monomer 152 with charges may generate charged ions. Thus, the distribution of the reactive monomer 152 with charges and the charged ions may change so as to deteriorate the performance of the liquid crystal panel. Specifically, after being driven for a long time period, the reactive monomer 152 with charges and the charges ions within the liquid crystal layer 150 are separated according to their polarity. The separated reactive monomer 152 and the charged ions consumes a portion of the bias voltage applied to the liquid crystal layer, which results in the screen effect. In addition, the reactive monomer 152 with charges and the charged ions generate parasitic potential within the liquid crystal panel, which leads to V_com shift.